In cutting, a coated tool in which a TiCN film or an aluminum oxide film is coated on the surface of a cemented carbide substrate has frequently been used. As the prior art of the coated tool, there is a coated material at least partially coated with one or more refractory layers of which at least one layer is a layer of alumina, said alumina layer has a thickness of d=0.5-25 μm, and consisting of a single phase α-structure having a grain size (S), said grain size (S) being 0.5 μm<S<1 μm for 0.5 μm<d<2.5 μm, and said grain size (S) being 0.5 μm<S<3 μm for 2.5 μm<d<25 μm, said alumina layer exhibits a texture coefficient (TC) greater than 1.3 for the (012) growth direction of the equivalent crystallographic planes defined by the following formula,
                                          TC            ⁡                          (              012              )                                =                                                    I                ⁡                                  (                  012                  )                                                                              I                  o                                ⁡                                  (                  012                  )                                                      ⁢                                          {                                                      1                    n                                    ⁢                                      ∑                                                                  I                        ⁡                                                  (                          hkl                          )                                                                                                                      I                          o                                                ⁡                                                  (                          hkl                          )                                                                                                                    }                                            -                1                                                    ,                    Formula      wherein I(hkl)=measured intensity of the (hkl) reflection, Io(hkl)=standard intensity of the ASTM standard power pattern diffraction data, n=number of reflections, and (hkl) reflection are (012), (104), (110), (113), (024), (116) (for example, see Patent Literature 1.). However, the coated material involves the problem that it cannot show sufficient performances in a processing requiring chipping resistance, in particular, in cutting of a steel.
Also, there is a coated cemented carbide in which an α-type aluminum oxide film showing TC(1,0,−1,4)=3.39, TC(1,0,−1,2)=0.27 and TC(1,0,−1,4)/TC(1,0,−1,2)=12.6 is coated on the surface of a cemented carbide to which a TiN film has been coated (for example, see Non-Patent Literature 1, p. 417, Table 2.). However, this coated cemented carbide has extremely coarse α-type aluminum oxide grains in the α-type aluminum oxide film, so that there is a problem that it is inferior in wear resistance at high temperature.    [Patent Literature 1] JP H06-316758A    [Non-Patent Literature 1] written by Chul-Soon Park, et al., “The effect of reaction condition on the crystallographic orientation and surface morphology of chemical vapor deposited Al2O3”, Proceedings of the 4th European Conference on Chemical Vapour Deposition, published by Philips Centre Manuf. Technol, Eindoven, Netherlands, 1983, P. 410-420